1. Field of the Invention
The present invention relates to a wheel hub clutch assembly for automotive vehicles of the four-wheel drive type, and more particularly to an improvement of a wheel hub clutch assembly arranged to automatically couple and uncouple a wheel hub to and from a driveable axle so as to selectively provide four-wheel drive or two-wheel drive.
2. Background of the Art
Such a wheel hub clutch assembly as described above comprises a cylindrical body attached to a wheel hub, an inner sleeve contained within the cylindrical body and fixedly mounted on a driveable axle, a clutch member splined to the inner sleeve to be maintained in its disengaged position during operation for two-wheel drive and to be engaged with the body in clutching operation to drivingly couple the wheel hub to the axle for four-wheel drive, a cam ring formed at one side thereof with a cam face and rotatably mounted on the inner sleeve, a cam follower arranged between the clutch member and the cam ring and splined to the inner sleeve to cooperate with the cam face of the cam ring to be axially moved to and from the clutch member in response to rotation of the inner sleeve, a return spring for loading the cam follower toward the cam face of the cam ring, means for connecting the cam follower with the clutch member, a brake assembly mounted within the cylindrical body and associated with the cam ring for applying the brake to the cam ring by engagement therewith in response to rotation of the cam follower, and a slide ring rotatably coupled over the cam ring and associated with the cam follower and the brake assembly for releasing the brake by engagement with the brake assembly when rotated by engagement with the cam follower. For the actual practice of the wheel hub clutch assembly, various tests and experiments have been conducted by the inventors. In these tests and experiments, it has been observed that the cam ring may not be disengaged from the brake assembly when the slide ring is rotated by engagement with the cam follower to release the brake in clutching operation. This causes undesired drag torque in the wheel hub clutch assembly during operation for four-wheel drive, resulting in defacement of the brake assembly in a short period of time and loss of the power.